He may have been earth’s rarest creature, but Lonesome George’s fate has been a common one for megafauna ever since humans came along. The Americas were once a surreal dreamscape of giant mammals, from short-faced bears the size of Ford Explorers to monstrous dire wolves to giant sloths larger than today’s elephants. They all suddenly disappeared around 10,000 B.C., not long after the first people are believed to have made their way down from the Bering land bridge.

Advertisement

Some paleobiologists blame the die-off on climate change, since it also coincided with the end of the last Ice Age. But extinctions have continued at a rapid clip throughout the ensuing Holocene Epoch, in which humans have come to dominate the globe. This has led to fears that we’re in the midst of a Sixth Great Extinction. (The fifth was 65 million years ago and involved dinosaurs.)

Megafauna are a tiny fraction of the thousands of species that vanish each year, but that’s because there weren’t that many of them to begin with. Of those that remain, many are hanging on in tiny numbers.

Lonesome George, who outlived his last relatives by decades, was an extreme example. (His kin were apparently done in by feral goats, which demolished the local vegetation after humans introduced them to the island.) But there are only a few hundred Siberian tigers, fewer than 1,000 mountain gorillas, and a few thousand black rhinoceroses. (The Western black rhino, a subspecies, was declared extinct just last year.) And if there are any remaining Baiji—also known as Chinese river dolphins—they probably number in the single digits.

When Galapagos National Park officials first spotted Lonesome George in 1971, they were overjoyed—they had thought his group extinct. They tried for decades to entice him to mate with female tortoises from neighboring islands, but without success.

It’s tempting to think that his kind could have lived on if only he had managed to reproduce. But while conservation efforts can sometimes help endangered species rebound, Lonesome George’s case reminds us that there are limits to what can be accomplished once a population dwindles to critical levels. The Baiji today may or may not be quite as lonesome as Lonesome George, but they are almost certainly headed for the same fate.

Some far-sighted conservationists have called for the United Nations to establish a global DNA bank so humans can study creatures even after they’re extinct. That’s a wise idea. But it's folly to imagine that these animals will someday be brought back to roam the land, Jurassic Park style. Even if they could be reconstituted, they’d be re-entering habitats different than those for which they evolved, and in numbers too small to sustain.

If we’re to avoid a future in which megafauna are a thing of the past, we can’t count on a Noah’s Ark full of Lonesome Georges.